This is an application for competitive renewal of a program project grant which has been active for 34 years. It involves many investigators and many different projects all relating to the improvement of the results of organ transplantation. The basic overall OBJECTIVES of this grant are to: 1. analyze and isolate the clinical problems involved in organ transplantation and precisely document clinical laboratory correlations; 2. organize clinical trials and experimental approaches based on available data, to solve clinical problems. Within these objectives, all projects are organized into two essential AIMS: AIM 1: TO PREVENT ORGAN DESTRUCTION. This includes not only immunological manipulations designed to prevent rejection but also those designed to prevent nonimmunologic graft loss, to prolong patient survival, and to modify or control drug toxicity and recurrent disease; AIM 2: TO MAXIMIZE REHABILITATION: The focus here is on minimizing complications and maximizing compliance with the immunosuppressive regimen. Within this framework, the current applications include projects addressing morbidity, mortality, and late graft loss (2 projects), chronic graft loss (3 projects), morbidity from avascular necrosis (1 project), and long-term living donor follow-up (1 project). The 2 Cores--Clinical and Administrative--support all projects.